Note: Descriptions are shown in the official language in which they were submitted.
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OVER-THE-NEEDLE PEEL-AWAY SHEATH CATHETER INTRODUCER
Background of the Invention
Field of the Invention
[0001] This invention is in the field of peel-away catheter introducers and
more particularly in the field of peel-away catheter introducers for neonatal
and
premature infants whose limbs and veins are extremely small.
Prior Art
[0002] Catheter introducers are typically used in conjunction with
peripherally inserted central catheters (PICC), guide wires or other
relatively long,
thin and flexible medical devices, to facilitate insertion and placement of
catheters
or other medical devices into the patients' vasculature. A conventional peel-
away
catheter introducer, also called a peelable or splittable catheter introducer,
comprises a hub with a pair of wings extending transversely of the proximal
end
of the hub and a sheath extending distally of the distal end of the hub. With
such
a catheter introducer an introducer needle is positionable through the
introducer
hub with the sharp distal tip of the needle extending distally of the distal
end of
the sheath. As used herein, the term proximal refers to a location on the
device
closest to the clinician using the device. Conversely, the term distal refers
to a
location on the device farthest from the clinician, such as the distal tip of
the
device to be inserted into a vein. Furthermore, the hub and sheath components
each have a proximal end and a distal end. Some prior art introducers also
include a funnel-like element at the proximal end of the hub to facilitate
introduction of a needle for venipuncture or introduction of a catheter or
guide
wire thereafter.
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[0003] When using a conventional peel-away catheter introducer the
clinician grasps the needle hub along with the introducer hub and proceeds to
insert the distal portions of the needle and introducer sheath at the selected
site
into the patient's skin. The clinician continues to advance the device until
venipuncture has been confirmed. This confirmation is usually done visually
when
the clinician sees blood entering a flashback chamber formed in the needle hub
at
the proximal end of the needle. After venipuncture has been confirmed, the
clinician advances the sheath portion of the introducer distally into the
patient's
vein and the needle is withdrawn. With the catheter introducer properly
placed,
the clinician can then insert a catheter, guide wire or other relatively long,
thin
and flexible medical device, into the proximal opening of the sheath and
continue
to advance the catheter or other device through the catheter introducer until
it is
properly placed in the patient's vasculature. After placement of the catheter
or
other device, the clinician withdraws the introducer proximally out of the
venipuncture site. The clinician then splits the introducer into its two
separate
halves by some combination of twisting and/or pulling apart of the wings along
tear lines in the top and bottom walls of the introducer until the two halves
of the
introducer hub and sheath split apart.
[00041 When used on neonatal patients conventional over-the-needle peel-
away catheter introducers are often awkward and difficult to employ. One
critical
concern is the insertion angle or angle of attack after initial piercing of
the tissue,
namely the angle of the introducer needle axis relative to the surface of the
patient's skin during venipuncture. An infant's vein is so tiny and so close
to the
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surface that with insertion proceeding at any typical insertion angle through
the
near wall of the vein, the needle could easily puncture the far wall of the
vein.
[0005] Early prior art introducers were designed and developed for adults.
Conventional introducers have structure which automatically forces
venipuncture
and advancement of the catheter to occur at a substantially higher angle than
optimal for neonatal patients, because the construction of these introducers
leads
to a shape and thickness of the bottom of the introducer hub and of the bottom
of
the wings which causes the proximal part of the introducer to remain elevated
and
away from the surface of the skin. Such structure is not a problem with
introducers for adults because the veins are far larger and more readily
discernable and accessible. With advances in medical diagnosis and treatment,
there is far greater application of venipuncture in neonatal patients, and
thus
there has developed a need for a catheter introducer that overcomes the above-
described risks associated with venipuncture in neonatal patients or at least
renders the venipuncture procedure safer, easier and quicker.
[0006] As limitations and/or problems became apparent when seeking to
use these devices with infants, efforts at improvements began to appear.
Disclosure in one prior art patent, U.S. Patent No. 6,273,871, alleges to
address
and solve this problem, but ultimately does not. As seen in Fig. 2 and
particularly
in Fig. 3 of this patent, there is a substantial bulk of material in the hub
70 below
the bottom of the sheath 60. The thickness of this material below the sheath
means that the position of the introducer above the skin and the resultant
insertion angle will always be substantial. This '871 Patent alleges to reduce
the
insertion angle by altering the center of mass of the needle hub, whereas the
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present invention concerns the insertion angle primarily after the needle is
removed, which is a different issue and requires a different approach.
[0007] U.S. Patent No. 5,221,263 discloses another peel-away catheter
where the hub 20 provides a full housing for the sheath's proximal end which
is
thus elevated and cannot lie flat on the patient's skin.
[0008] U.S. Patent No. 5,334,157 discloses another catheter introducer
which is a non-peel-away type, but which has a flat bottom. This device also
has
the sheath substantially elevated and within a separate housing.
[0009] The present invention employs a novel and substantially different
construction which provides a new and improved catheter introducer along with
a
new method of making this catheter introducer and a new method of using it.
Summary of the Invention
[0010] It is an object of this invention to provide an over-the-needle peel-
away sheath catheter introducer that allows a very low insertion angle during
venipuncture. For convenience and simplification of terminology, references
hereinafter to "catheter introducer" will mean "over-the-needle peel-away
catheter
introducer".
[0011] It is another object of this invention to provide a catheter introducer
that allows an insertion angle during advancement that is as low as one-two
degrees for the introducer and needle combination and as low as zero degrees
for
the introducer without the needle.
[0012] It is a further object of this invention to provide a catheter
introducer whose sheath is situated at the bottom of said introducer with the
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lumen of said sheath located above the bottom of the introducer by the wall
thickness of said sheath.
[0013] In contrast to prior art catheter introducers formed of a hub housing
about a sheath and its lumen, it is a further object of this invention to
provide in
the hub a lumen portion in substitution of the sheath and its lumen.
[0014] It is a still further object of this invention to provide a catheter
introducer where the bottom of the sheath, the bottom of the wings and the
bottom of the hub define a generally flat plane.
[0015] Another object of this invention is to provide a catheter introducer
which includes a funnel element at the proximal end of the hub, where the
bottom
of the funnel is at substantially the same elevation as the bottom of the hub
and
the bottom of the wings.
[0016] An additional object of this invention is to provide a hub for a
catheter introducer having a sheath therethrough, where the hub comprises left
and right halves whose opposing side walls define sides of the lumen, and
where
the top and bottom walls of the sheath comprise material extending between
said
sides.
[0017] A further object of this invention is to form a catheter introducer
hub, wings and funnel all as a contiguous molded body.
[0018] Another object of this invention is to provide non-peel-away catheter
introducers with the features described above.
[0019] A still further object of this invention is to provide a method of
injection molding the new catheter introducer employing a removable core pin
that extends through the cavity forming the hub and through the lumen of a
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sheath whose proximal end is positioned axially within the mold cavity where
the
distal end of the hub will be formed, and where the hub halves and top and
bottom walls are overmolded about the core pin which pin defines a lumen
extending through the hub.
[0020] An additional object is to provide a method of introducing a catheter
or guide wire into a vein of a patient by providing a catheter introducer
whose
thickness below the lumen is no more than the thickness of the lumen wall, so
that the angle of insertion (or angle of attack) can be extremely low and
essentially zero degrees after the introducer needle is removed and the
introducer
is being advanced into the vein. Here, the introducer is essentially parallel
to or
flat against the patient's skin, with the catheter spaced above the skin by
only the
wall thickness of the sheath. Furthermore, the preferred embodiment of the new
introducer has an essentially flat bottom where the bottom surfaces of the
sheath
and of the hub and of the funnel define a plane which is at the lowest
elevation of
the introducer and which provides stability of the introducer from rocking
from
side to side or from rotation about a vertical axis.
[0021] The present invention thus comprises a new catheter introducer
structure, a new method of manufacturing this introducer and a new method of
introducing a catheter or guide wire using the new introducer. These three
embodiments are exemplified by the descriptions presented below.
[0022] A first embodiment of the new catheter introducer comprises:
a. a hub having opposite proximal and distal ends, said hub
comprising right and left halves extending axially between said proximal and
distal ends, with a hub lumen extending axially between said halves,
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b. a wing extending from each of said halves transversely of said
hub lumen,
c. a funnel formed of converging cylindrical walls having a proximal
end opening of first diameter and a distal end opening of diameter less than
that
of said first diameter, said distal end of said funnel joined to said proximal
end of
said hub, said funnel having a lumen communicating with said hub lumen, and
d. a sheath comprising a cylindrical wall formed as a tube having a
proximal end joined to said distal end of said hub, a distal end and a sheath
lumen
which communicates with said hub lumen,
said right and left halves of said hub having adjacent and spaced
apart inner wall surfaces, said hub further comprising top and bottom walls
extending between and joining said spaced apart inner wall surfaces, with said
hub lumen being defined by said spaced apart inner wall surfaces and said top
and bottom walls, said introducer including tear lines along the length of
said
funnel, hub and sheath for adapting said introducer to be split into two parts
when said wings are pulled away from each other.
[0023] If desired, this structure may be employed with an introducer that
does not include a funnel part or one where the funnel is incorporated into
the
hub instead of extending proximally from the hub.
[0024] The new invention further comprises a method of injection molding
the new catheter introducer having a funnel entry part, a hub and a sheath and
a
continuous lumen therethrough, wherein said lumen in said hub is defined by
left
and right hub halves and top and bottom walls extending between and joining
said halves, and wherein an axial extension of said sheath's proximal end is
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situated in the distal part of said hub and is coaxial and coextensive with
said
lumen in said hub, comprising the steps:
a. providing an injection mold with a cavity to define said
funnel entry part and said hub,
b. positioning a sheath with its proximal end axially within the
cavity where the distal end of the hub will be formed,
c. removably positioning a core pin axially through said cavity
where the lumens of the hub and funnel entry parts will be situated and
through
said sheath lumen,
d. injecting plastic into said mold which plastic surrounds said
core pin thus forming right and left halves of said hub, top and bottom walls
joining said left and right halves, and a lumen in the space occupied by said
core
pin between said right and left halves and between said top and bottom walls,
which lumen is coaxial and coextensive with said lumen in said proximal end of
said sheath situated in said cavity, the plastic of said top and bottom walls
and of
said right and left halves bonding with the tubular end wall of said proximal
end
of said sheath, and
e. opening said mold and removing said core pin and removing
said catheter introducer.
[0025] The new invention further includes a method of using the new
introducer comprising the steps:
a. providing a catheter introducer comprising a funnel entry
part, a central hub part and a distal sheath part, with a continuous lumen
extending through said parts, where said introducer has a bottom surface which
is
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the lowest part of said introducer, and where said continuous lumen is spaced
from said bottom surface a distance no greater than the thickness of said
lumen
wall,
b. inserting an introducer needle through said continuous lumen
until the distal end of said needle extends distally out of the distal end of
said
sheath,
c. positioning said catheter needle and catheter introducer for
insertion,
d. piercing and dilating the skin and the near wall of the vein of
the patient with the distal ends of said introducer needle and of said
introducer
sheath,
e. after initial piercing of the skin and of the near wall of the
vein and flashback has been observed, reducing said insertion angle by
lowering
said introducer's proximal end until said bottom surface of said introducer
lies
generally parallel to the patient's skin, and advancing said needle and
introducer
sheath into said vein a predetermined distance, to ensure that the distal ends
of
both the introducer needle and catheter introducer sheath are in the patient's
vein,
f. advancing said introducer sheath distally further into the vein
and withdrawing said needle out of the introducer,
g. introducing a catheter or guide wire through said continuous
lumen in said introducer and into the patient's vein,
h. withdrawing said introducer sheath proximally out of said
vein and skin of the patient, and
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i. splitting said introducer hub and funnel entry parts and
peeling said introducer hub part and sheath into two parts and removing them
from said catheter.
[0026] Further features and advantages of the invention as well as the
structure and operation of various embodiments of the present invention are
described in detail below with reference to the accompanying drawings.
Brief Description of the Drawings
[0027] Fig. 1 is a top perspective view of the new catheter introducer.
[0028] Fig. 2 is a top plan view thereof.
[00291 Fig. 3 is a left side elevational view thereof.
[0030] Fig. 4 is a top sectional view taken along line 4-4 in Fig. 3.
[0031] Fig. 5 is a sectional view taken along line 5-5 in Fig. 2.
[0032] Fig. 6 is a sectional view taken along line 6-6 in Fig. 2.
[0033] Fig. 7 is a sectional view taken along line 7-7 in Fig. 2.
[0034] Fig. 8 is a sectional view taken along line 8-8 in Fig. 2.
[0035] Fig. 9 is a front end elevational view of the introducer in Fig. 1.
[0036] Fig. 10 is a top perspective view of the new introducer with an
introducer needle during initial venipuncture.
[0037] Fig. 11 is a view similar to Fig. 10, but at a further stage of
venipuncture.
[0038] Fig. 12 is an elevational view of the new introducer during
venipuncture.
[00391 Fig. 13 is a top perspective view of an inserted catheter after
withdrawal and splitting of the introducer.
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[0040] Fig. 14 is a schematic top plan view representing injection molding
of the new introducer.
[0041] Fig. 15 is a sectional view taken along line 15-15 in Fig. 14.
Detailed Descri-ption of the Preferred Embodiments
[0042] As seen in Figs. 1-4 the new catheter introducer 10 comprises a hub
12 having proximal and distal ends 13, 14, a funnel 15 having proximal and
distal
ends 16, 17, and a sheath 18 having proximal and distal ends 19, 20.
[0043] The hub 12 is formed of opposite left and right halves 21, 22 with a
lumen 23 between them. As seen in Fig. 1-6 the lumen 23 is defined by its side
walls 24, 25 which are opposing surfaces of said left and right halves of the
hub,
and by top and bottom thin walls 26, 27 which extend between said halves.
[0044] As seen in Figs. 1-5, wings 30, 31 extend transversely from said hub
halves. These wings are situated at the proximal end 13 of the hub. The wings
30, 31 comprise generally flat blades which curve downward as they approach
hub halves 21, 22. The wings have substantially flat bottom surfaces 40, 41 as
seen in Figs. 5 and 6. The bottom surfaces of these wings and the bottom
surface
of hub 12 and of funnel 15 are all in substantially the same plane,
representing
the lowest part of the entire introducer.
[0045] Funnel 15 as seen in Figs. 1-5 and 9 is a converging cylindrical body
whose lumen 33 has a larger proximal end opening and a smaller distal end
opening. The distal end 17 of funnel 15 is joined to the proximal end 13 of
hub
12, with their respective lumens aligned and of the same diameter. Funnel 15
at
its proximal end 16 defines in end view a generally flat bottom 37, generally
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parallel side walls 38 extending upward from said bottom, and a generally
round
top 39.
[0046] The sheath 18 is a hollow tube whose proximal end extension 19A,
as seen in Figs. 1, 2 and 4, is situated proximally inward of the distal end
14 of
hub 12. The hub is molded onto the proximal end extension 19A of sheath 18, as
described in greater detail in later sections herein.
[0047] As seen in Figs. 4 and 6, sheath 18 is a tube formed of a cylindrical
wall of generally uniform thickness. The top and bottom walls 26, 27 of the
hub
lumen 23 and said side walls 24, 25 thereof form a tube that is essentially an
extension of the sheath, extending from proximal end extension 19A of the
sheath
to proximal end 13 of the hub. Said top and bottom walls 26, 27 have thickness
essentially the same as said sheath wall thickness, which is conventionally
about
.006 inches.
[0048] The sheath is formed of suitable polymeric material, for example,
high density polyethylene plastic, and is made by extrusion or other means
prior
to and independently of the molding of said hub. The hub halves 21, 22, wings
30, 31, top and bottom walls 26, 27 and funnel 15 are molded, also of suitable
polymeric material, for example, high density polyethylene, in a single stage,
where the hub halves 21, 22 are molded onto and bonded with the proximal end
19 of sheath 18. Typically, a radiopaque stripe is co-extruded along the
length of
the sheath.
[00491 In summary, the new introducer is injection molded as represented
schematically in Figs. 14 and 15 which show how the hub 12 is overmolded onto
the sheath's proximal extension end 19A. Using conventional injection molding
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apparatus, the mold as represented schematically by the bottom and top halves
46, 46A of the mold, defines a cavity 47 for forming the hub, wings, and
funnel
shown by dashed reference lines to reference the numbers 12, 30, 31 and 15
respectively. Alternative side-by-side mold halves could be used. In the
actual
molding process the distal portion of core pin 48 is positioned in the lumen
of the
preformed sheath 18 to maintain its patency. The sheath then has its proximal
end extension 19A positioned in the portion of the mold that forms the distal
end
of the hub, while the proximal portion of the core pin extends out of the
sheath
and through the hub area 12. Thereafter, molding the hub circumferentially
about core pin 48 defines, upon removal of the pin, the hub lumen.
[0050] The core pin 48 is enlarged at its proximal end to define the
diverging lumen of the funnel 15. In this manner the hub lumen 23 has internal
diameter the same as that of the sheath 18 and of the distal end of the funnel
15.
[0051] As seen in Fig. 6, the hub lumen 23 is defined more particularly by
opposing side walls 24, 25 of the hub halves 21, 22 and by top and bottom
walls
26, 27 extending between and joining the hub halves of these walls being
molded
over the core pin 48 and over the proximal end extension 19A of sheath 18.
[0052] The final phase of manufacture of this peel-away catheter introducer
is to form tear lines, 43, 44 in the center of the top and bottom surfaces,
along the
entire length of the sheath, hub and funnel, as seen in Figs. 2 and 5-9. The
tear
lines can be made in a number of ways, including but not limited to, razor
cuts
and laser cuts. The depth of the cuts may be about .003 inches for certain
neonatal introducers or commonly about fifty percent of the wall thickness,
the
guideline being that the material remaining after the cut should be strong
enough
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to maintain the product's structure and function and weak enough to be readily
tearable by clinicians using these products. The wall thicknesses of the
sheath, of
the hub and of the funnel are substantially the same, such that laser cutting
of the
tear lines can be uniform and swift, so that the resultant skived or scored
walls
will tear apart easily and uniformly along their length.
[0053] As seen in Figs. 10 and 11, when venipuncture is initiated as
introducer sheath 18 with needle 50 is directed toward the incision site, the
skin is
pierced and entry into a vein 54 begins. In accordance with the present
invention,
very promptly after entry of the distal ends of the needle and introducer
sheath
50, 18, as seen in Figs. 10 and 11, the introducer and needle combination is
lowered from the initial angle of insertion to a very low angle or
substantially
parallel to or flat against the skin, as seen in Fig. 12, to allow advancement
of the
needle and sheath combination 50, 18 into the vein 54 followed by withdrawal
of
the needle. By this method and with this device, the risk of piercing the far
wall
of the vein is greatly reduced. The low angle is possible because the new
structure
has eliminated all material below the sheath, while still providing a hub and
wings
that are strong, stable and readily peelable at the appropriate time. More
specifically, the overmolded hub defines bottom lumen walls no lower than the
sheath's bottom walls and of substantially the same thickness as the sheath's
bottom walls. The walls of the hub and sheath lumen, when similarly skived or
scored, present the same tear strength characteristics. The needle or stylet
50 is
well known in the prior art and is typically made of stainless steel with the
needle's hub part 52 made of any suitable polymeric material, for example
acrylic
or K-resin.
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[0054] Following insertion of catheter 61 through the introducer into the
vein, Fig. 13 illustrates withdrawal of the introducer sheath 18, shown in
dashed
lines, from the incision site 60 while the catheter 61 remains. In a
conventional
manner the wings 30, 31 are twisted upward and/or downward as indicated by
arrows 62, 63 respectively until the sheath, hub and funnel 18, 12, 15 break
apart
along the top and bottom tear lines. The two halves of the introducer 64, 65
are
shown separated and peeled apart when pulled in the directions of arrows 66
and
67.
[0055] While various embodiments of the present invention have been
described above, it should be understood that they have been presented by way
of
example and not limitation. It will be apparent to persons skilled in the
relevant
art that various changes in form and detail can be made therein without
departing
from the spirit and scope of the invention. Thus, the present invention should
not
be limited by any of the above described exemplary embodiments, but should be
defined only in accordance with the following claims and their equivalents.
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